Implantable medical devices have long utilized medical electrical leads, which include an electrode adapted for pacing myocardial tissue via intimate tissue contact with a surface of the electrode. An alternative pacing electrode, generally described by Parsonnet et al. as a differential current density (DCD) electrode in “Clinical use of a new transvenous electrode” Annals New York Academy of Science, Oct. 30, 1969, 167:756-760, includes an electrode surface, in the form of a cylinder, contained within an insulative housing and thus separated from tissue contact. The DCD electrode described by Parsonnet et al. makes stimulating contact with endocardial tissue via a hole or port in the insulative housing; when a current is applied the density of the current at the electrode surface is low relative to that at the hole, thus the differential current density. A higher current density at the interface between the hole and endocardial tissue results in lower stimulation thresholds, while a lower current density along the electrode surface within the insulative housing minimizes polarization; polarization, resulting from an accumulation of charge on an electrode surface post-stimulation, produces an after-potential that hinders accurate sensing of intrinsic cardiac activity. Such an electrode necessarily includes an ionically conductive medium filling a void between the electrode surface contained within the insulative housing and the hole in contact with the myocardium. A stable conductive medium incorporated into a DCD-type electrode along with means to maintain stable long-term contact between a hole or a port of such an electrode and excitable tissue are desirable.